Apparatus and method for calibrating a polishing head

Abstract

An apparatus for calibrating the centering of polishing heads in a polishing machine that is equipped with a plurality of spindles onto which polishing heads are mounted and a method for using such apparatus are disclosed. In the apparatus, a calibration disc is provided which has a hollow shaft mounted at a center of the bottom surface of the disc. A centering pin slidingly engaging an elongated cavity in the hollow shaft such that its protruded tip portion may be adjusted by using a locking device such as a set screw for different calibration procedures. The present invention novel apparatus can be used to calibrate the positioning of a polishing head mounted in a spindle with a pedestal in a load cup that is equipped with a center alignment aperture. The calibration can be conducted not only in the X, Y direction (or in the circumferential direction) of the spindle movement, but also in the Z direction (or a sweep direction) of the traversing spindle that occurs during a polishing operation.

The embodiment of the invention in which an exclusive property or privilege is claimed are defined as follows: 
     
       1. An apparatus for calibrating the centering of polishing heads in a chemical mechanical polishing (CMP) machine equipped with a plurality of spindles for mounting said polishing heads comprising: a circular disc having top and bottom parallel planar surfaces,   a hollow shaft having an elongated cavity therein for slidingly engaging a pin through an open end of the cavity, said hollow shaft having external male threads at one end for engaging female threads in a center aperture on said bottom surface of the disc,   a pin for slidingly engaging said elongated cavity in said hollow shaft such that said pin extends out of or retracts into said hollow shaft, and   a locking means for locking position of said pin in said elongated cavity.   
     
     
       2. An apparatus for calibrating the centering of polishing heads in a CMP machine equipped with a plurality of spindles for mounting said polishing heads according to claim 1, wherein said plurality of spindles comprises four spindles. 
     
     
       3. An apparatus for calibrating the centering of polishing heads in a CMP machine equipped with a plurality of spindles for mounting said polishing heads according to claim 1, wherein said pin being adapted for penetrating a center alignment aperture in a pedestal positioned under said spindle such that the X, Y parameters of said spindle are adjusted for calibrating the centering. 
     
     
       4. An apparatus for calibrating the centering of polishing heads in a CMP machine equipped with a plurality of spindles for mounting said polishing heads according to claim 1 further comprising a mounting means for removably mounting said circular disc to said spindle with said center pinpointed downwardly. 
     
     
       5. An apparatus for calibrating the centering of polishing heads in a CMP machine equipped with a plurality of spindles for mounting said polishing heads according to claim 4, wherein said mounting means further comprising: a locating means for aligning said circular disc to said spindle, and   a clamping means for removably mounting said circular disc to said spindle.   
     
     
       6. An apparatus for calibrating the centering of polishing heads in a CMP machine equipped with a plurality of spindles for mounting said polishing heads according to claim 1, wherein said pin being adapted for penetrating a center alignment aperture in a pedestal positioned under said spindle. 
     
     
       7. An apparatus for calibrating the centering of polishing heads in a polishing machine equipped with a plurality of spindles for mounting said polishing heads comprising: a calibration disc having top and bottom parallel planar surfaces, said bottom surface being equipped with a pin at its center projecting away from and perpendicular to said planar bottom surface, said center pin being adapted for aligning a spindle on which the calibration disc is mounted with a center alignment aperture in a pedestal generally positioned below said spindle, and   a mounting means for removably mounting said calibration disc to said spindle with said center pin pointed downwardly.   
     
     
       8. An apparatus for calibrating the centering of polishing heads in a polishing machine equipped with a plurality of spindles for mounting said polishing heads according to claim 7, wherein said pin at the center of the bottom surface further comprises: a hollow shaft having an elongated cavity therein for sliding engagement with a pin through an open end of said elongated cavity, said hollow shaft having external male threads at one end for engaging an aperture having matching female threads at a center of said bottom surface,   a pin for sliding engagement with said elongated cavity in said hollow shaft such that said pin extends out of or retracts into said hollow shaft, and   a locking means for locking position of said pin in said elongated cavity.   
     
     
       9. An apparatus for calibrating the center of polishing heads in a polishing machine equipped with a plurality of spindles for mounting said polishing heads according to claim 7, wherein said mounting means for mounting said calibration disc to one of said plurality of spindles further comprising locating means for said disc and said spindle. 
     
     
       10. An apparatus for calibrating the centering of polishing heads in a polishing machine equipped with a plurality of spindles for mounting said polishing heads according to claim 7, wherein said mounting means comprises at least one C-clamp for clamping said disc to one of said plurality of spindles. 
     
     
       11. An apparatus for calibrating the centering of polishing heads in a polishing machine equipped with a plurality of spindles for mounting said polishing heads according to claim 7, wherein said calibration disc is in a circular shape. 
     
     
       12. An apparatus for calibrating the centering of polishing heads in a polishing machine equipped with a plurality of spindles for mounting said polishing heads according to claim 7, wherein said calibration disc is in a square shape. 
     
     
       13. An apparatus for calibrating the centering of polishing heads in a polishing machine equipped with a plurality of spindles for mounting said polishing heads according to claim 7, wherein said pin is adapted to align a spindle on which the calibration disc is mounted with a center alignment aperture in a pedestal for loading/unloading a substrate to be polished. 
     
     
       14. A method for calibrating the centering of polishing heads in a polishing machine equipped with a plurality of spindles for mounting said polishing heads comprising the steps of: providing a calibration disc having top and bottom parallel planar surfaces, said bottom surface being equipped with a pin at its center projecting away from and perpendicular to said planar bottom surface, said center pin being adapted for aligning a spindle on which the calibration disc is mounted with a center alignment aperture in a pedestal positioned below said spindle,   mounting said calibration disc to a spindle with said center pin pointed downwardly,   positioning said spindle over said pedestal positioned below said spindle,   aligning said center pin on said calibration disc to said center alignment aperture in said pedestal, and   adjusting X and Y axis of said spindle until said center pin on said calibration disc coincides with said center alignment aperture in said pedestal.   
     
     
       15. A method for calibrating the centering of polishing heads in a polishing machine equipped with a plurality of spindles for mounting said polishing heads according to claim 14, wherein said step of providing a pin at the center of the bottom surface further comprising the steps of: providing a hollow shaft having an elongated cavity therein for sliding engagement with a pin through an opening end of said elongated cavity, said hollow shaft having external male threads at one end for engaging an aperture having matching female threads at a center of said bottom surface,   providing a pin for sliding engagement with said elongated cavity in said hollow shaft such that said pin extends out of or retracts into said hollow shaft, and   providing a locking means for locking a position of said pin in said elongated cavity.   
     
     
       16. A method for calibrating the centering of polishing heads in a polishing machine equipped with a plurality of spindles for mounting said polishing heads according to claim 14, wherein said step of providing said mounting means further comprising: providing a locating means for the precise positioning of said calibration disc to one of said plurality of spindles, and   providing a C-clamp for clamping said disc to one of said plurality of spindles.   
     
     
       17. A method for calibrating the centering of polishing heads in a polishing machine equipped with a plurality of spindles for mounting said polishing heads according to claim 14 further comprising the step of providing said calibration disc in a circular shape. 
     
     
       18. A method for calibrating the centering of polishing heads in a polishing machine equipped with a plurality of spindles for mounting said polishing heads according to claim 14 further comprising the step of providing four spindles for said plurality of spindles, and rotating 90° such that a second spindle is calibrated by the same steps. 
     
     
       19. A method for calibrating the centering of polishing heads in a polishing machine equipped with a plurality of spindles for mounting said polishing heads according to claim 14, wherein the method is used for calibrating the centering of polishing heads in a chemical mechanical polishing machine. 
     
     
       20. A method for calibrating the centering of polishing heads in a polishing machine equipped with a plurality of spindles for mounting said polishing heads according to claim 15 further comprising the step of locking said pin at a length sufficient to penetrate said center alignment aperture in said pedestal.